The invention relates to motor vehicle heating systems and more particularly to heating systems that more efficiently utilize the heat from the various fluids and gases used with internal combustion engines.
An object of the present invention is to provide an efficient system that is capable of removing or supplying heat from the internal combustion engine while employing the smallest possible number of parts and while facilitating multiple utilization of those parts.
This object is achieved according to the invention by providing an arrangement or system for heating the payload space, including a pipe leading into the atmosphere through which air is transportable, the pipe being divided into a first pipe branch and a second pipe branch, of which one branch pipe is provided with a first heat exchanger through which waste gases of the internal-combustion engine are flowed on one side of the exchanger. The arrangement also includes a second heat exchanger arranged downstream of the junction of the two pipe branches and a control device for dividing the air between the first and second pipe branches, the second heat exchanger having a liquid for cooling the internal-combustion engine flowed on one side of the exchanger.
In the system of the present invention a multiple utilization of the existing parts is possible. In the system, the air, in the case of high heat incidence and/or low heat demand, absorbs heat in the second heat exchanger from the liquid utilized for cooling the internal-combustion engine and discharges it outwards. In the case of low heat incidence and/or high heat demand, the air is heated by the waste gases and returns heat to the liquid and hence to the internal-combustion engine, so that the latter can attain its service temperature more rapidly and thus indirectly assist in the heating of the payload space.
In certain preferred embodiments of the present invention the second heat exchanger serves not only as an engine oil cooler, but also returns waste gas heat via the engine oil into the internal-combustion engine.
In certain preferred embodiments of the present invention the second heat exchanger utilizing cooling liquid, alone or in conjunction with a heat exchanger utilizing engine oil, facilitates the cooling of the cooling liquid by surrendering heat to the air flowing through said exchanger, or alternatively it may be used to accelerate the warming-up of the internal-combustion engine and to improve the heating of the payload space by absorbing heat from the air.
With the preferred embodiments of the present invention combustion air is fed at the most favorable temperature via an air intake pipe to the internal-combustion engine thus further improving the thermal economy of the engine.
In certain preferred embodiments of the present invention the system includes means for returning a portion of the air from the pipe leading to the atmosphere from a location downstream of the second heat exchanger back into said pipe at a location upstream of the bifurcation of the pipe into the first and second branches. The partial guidance of air in the pipe as ambient air further improves the thermal economy.
In certain preferred embodiments of the present invention air flowing through the pipe leading to the atmosphere is obtained from the payload space. This has a beneficial effect in that the air in the payload space fed from the pipe leading to the atmosphere is already heated at times of high heat demand and is frequently cooled at times of low heat demand.
In certain preferred embodiments of the present invention the second heat exchange is provided with the filling connection for the cooling liquid and has sufficient volume to allow for the expansion of the cooling liquid when it is heated. By this arrangement separate compensating and expansion tanks for the cooling liquid can be omitted and the number of parts used thereby reduced.
Further objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.